KVM: selftests: Refactor stable TSC check to use TEST_REQUIRE()

Refactor the nested TSC scaling test's check on a stable system TSC to
use TEST_REQUIRE() to do the heavy lifting when the system doesn't have
a stable TSC.  Using a helper+TEST_REQUIRE() eliminates the need for
gotos and a custom message.

Cc: Hao Ge <gehao@kylinos.cn>
Cc: Vipin Sharma <vipinsh@google.com>
Link: https://lore.kernel.org/r/20230406001724.706668-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
index fa03c8d..e710b6e 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
@@ -116,29 +116,21 @@ static void l1_guest_code(struct vmx_pages *vmx_pages)
        GUEST_DONE();
 }
 
-static void stable_tsc_check_supported(void)
+static bool system_has_stable_tsc(void)
 {
+       bool tsc_is_stable;
        FILE *fp;
        char buf[4];
 
        fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r");
        if (fp == NULL)
-               goto skip_test;
+               return false;
 
-       if (fgets(buf, sizeof(buf), fp) == NULL)
-               goto close_fp;
+       tsc_is_stable = fgets(buf, sizeof(buf), fp) &&
+                       !strncmp(buf, "tsc", sizeof(buf));
 
-       if (strncmp(buf, "tsc", sizeof(buf)))
-               goto close_fp;
-
-       fclose(fp);
-       return;
-
-close_fp:
        fclose(fp);
-skip_test:
-       print_skip("Kernel does not use TSC clocksource - assuming that host TSC is not stable");
-       exit(KSFT_SKIP);
+       return tsc_is_stable;
 }
 
 int main(int argc, char *argv[])
@@ -156,7 +148,7 @@ int main(int argc, char *argv[])
 
        TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
        TEST_REQUIRE(kvm_has_cap(KVM_CAP_TSC_CONTROL));
-       stable_tsc_check_supported();
+       TEST_REQUIRE(system_has_stable_tsc());
 
        /*
         * We set L1's scale factor to be a random number from 2 to 10.